The present invention generally relates to methods and apparatus for searching a desired track position or recording region on an information recording medium, and more particularly to a method and apparatus for automatically searching a desired track position or recording region on an information recording medium which comprises pre-recorded tracks and unrecorded tracks based on the existence and non-existence of a reproduced radio frequency (RF) signal reproduced from the information recording medium.
Information recording discs, especially video discs, are recorded with information signals from an inner peripheral position to an outer peripheral position of a recording region, for example, on a continuous pre-recorded track or consecutive pre-recorded tracks. However, among recordable discs, there are discs having the recording region thereof divided into a plurality of recording sections which are allocated for predetermined kinds of information signals such as a video signal. In such discs, the pre-recorded track is not continuous and the successive pre-recorded tracks have discontinuities. In other words, pre-recorded tracks and unrecorded tracks coexist in the recording region of such discs.
When playing the disc having the pre-recorded tracks and the unrecorded tracks formed at random in the recording region, there are cases where the user wishes to search for a starting track position of a first group of unrecorded tracks which occurs after a pre-recorded track which is being scanned in a reproduction mode, and cases where the user wishes to search for a starting position of a first group of pre-recorded tracks which occurs after an unrecorded track which is being scanned in a recording mode.
However, the search for the starting track position of an arbitrary group of tracks is difficult to carry out without an address information. For this reason, such a search is conventionally carried out by playing the disc in a normal reproduction mode and manually stopping the feeding of a reproducing means when the state of the reproduced signal changes. In other words, the user must monitor a reproduced picture on a monitoring display in the normal reproduction mode and manually stop the feeding of the reproducing means when the state of the reproduced picture changes. For example, when the user wishes to search for the starting track position of the first group of unrecorded tracks which occurs after the pre-recorded track which is being scanned in the normal reproduction mode, the user stops the feeding of the reproducing means when a reproduced picture is no longer obtained on the monitoring display. For this reason, in a case where one pre-recorded track exists within a group of unrecorded tracks or one unrecorded track exists within a group of pre-recorded tracks, for example, there is a problem in that the user may overlook the track position where the state of the reproduced picture changes because the scanning time of one track is extremely short. In addition, there is a big burden on the user because the user must constantly monitor the reproduced picture on the monitoring display while the search is carried out.
On the other hand, when recording a video signal amounting to a predetermined number of frames on the disc having the pre-recorded tracks and the unrecorded tracks formed at random in the recording region, it is necessary to search the existing position of a group of unrecorded tracks comprising a number of unrecorded tracks sufficient for recording the video signal amounting to the predetermined number of frames. In this case, the user may use a table or the like which contains frame numbers of pre-recorded tracks and unrecorded tracks when searching for the group of unrecorded tracks comprising the sufficient number of unrecorded tracks.
However, when there is no table containing such information, the user must search for the group of unrecorded tracks while monitoring the reproduced picture on the monitoring display, and the user must also discriminate whether or not the searched group of unrecorded tracks comprises a number of unrecorded tracks sufficient for recording the video signal amounting to the predetermined number of frames. Hence, there are problems in that the operation of searching for the group of unrecorded tracks and the operation of discriminating whether or not the searched group of unrecorded tracks comprises the sufficient number of unrecorded tracks are extremely difficult and troublesome to carry out.
In addition, in a case where the user wishes to record a video signal amounting to such a large number of frames on the disc having the pre-recorded tracks and the unrecorded tracks formed at random in the recording region that the video signal cannot be recorded within one group of unrecorded tracks, it is necessary to record the video signal in a plurality of groups of unrecorded tracks located at independent parts of the recording region on the disc. Furthermore, there is a case where the video signal should be recorded in different recording modes in each of the plurality of groups of unrecorded tracks. For example, when the video signal relates to an opening flower, it is desirable to observe the movements of the petals at a high speed, and the recording of the video signal is carried out in an interval recording mode in one group of unrecorded tracks. In the interval recording mode, the recording is carried out at predetermined intervals. On the other hand, the recording need not be carried out in sequence from the group of unrecorded tracks located in the inner peripheral part of the recording region to the group of unrecorded track located in the outer peripheral part of the recording region, and the sequence may be arbitrary.
Accordingly, it is desirable that a program recording can be carried out in which a plurality of groups of unrecorded tracks are set by manipulating a remote control key and the information signal such as the video signal is continuously and automatically recorded on the groups of unrecorded tracks in the set sequence.
However, it is necessary to prevent a duplex recording in which the information signal is erroneously recorded on a pre-recorded track which is pre-recorded with another information signal, since the other information signal will be erased by the new recording on the pre-recorded track. It is essential that the duplex recording is prevented in a type of information recording medium which can be recorded only once with an information signal, because the signal recorded on the pre-recorded track of this type of information recording medium cannot be erased. In other words, if the information signal is newly recorded on the pre-recorded track which is recorded with the previously recorded information signal, both the previously recorded information signal and the newly recorded information signal will be destroyed and neither the previously recorded information signal nor the newly recorded information signal can be reproduced at the time of a reproduction.
The present applicant has thus proposed a method and apparatus for preventing duplex recording on the information recording medium in a United States patent application Ser. No. 040,946 entitled "METHOD AND APPARATUS FOR PREVENTING DUPLEX RECORDING ON INFORMATION RECORDING MEDIUM" filed on Apr. 21, 1987 (U.S. Pat. No. 4,794,582) based on a Japanese Patent Application No. 94641/1986, so as to accurately discriminate the unrecorded tracks and the pre-recorded tracks and positively prevent the erroneous recording of the information signal on the pre-recorded tracks.
According to this previously proposed method and apparatus, an unrecorded track having a starting address where a recording is to be started is detected, a first pre-recorded track occurring after the unrecorded track is detected, an address of the first pre-recorded track is confirmed by reproducing address signals from vicinities of the first pre-recorded track, an information signal is recorded on unrecorded tracks occurring after the unrecorded track having the starting address, and the recording of the information signal is forcibly stopped at an unrecorded track having an address which is one less than the address of the first pre-recorded track.
The user makes a program (records the information signal) by referring to the table which identifies the unrecorded tracks on the disc which is played when carrying out the program recording described before, but there may be errors in the table and errors in the programming itself. When such errors exist, the user may be trying to record the information signal on the pre-recorded track.
According to the previously proposed method and apparatus, the recording of the information signal is forcibly stopped in the case where the user is trying erroneously to record the information signal on the pre-recorded track, and the program recording is ended at the halfway point. However, the forced stopping of the program recording is undesirable in this case because the original intent of the program recording is to record the information signal on the plurality of groups of unrecorded tracks as described before. In other words, the original intent of the program recording cannot be realized unless the program recording is carried out to the end.